The radio frequency (RF) transmissions of some portable communication devices, such as some cellular telephones, can interfere with a user's hearing aid. Such interference may cause an annoying and/or painful buzzing noise. In some countries, governmental design constraints have been or are being proposed for the RF transmissions of portable communication devices to exhibit a particular electric field and magnetic field behavior near an earpiece of the portable communication device to limit such interference.
In the United States, for example, the American National Standards Institute (ANSI) Accredited Standards Committee C63 on Electromagnetic Compatibility has defined standard ANSI C63.19 to establish compatibility between hearing aids and portable communication devices such as cellular telephones. ANSI C63.19 specifies that the RF transmissions of a portable communication device must have particular characteristics in the area of the portable communication device's earpiece (i.e., approximately where a person's hearing aid would be located during use with the communication device). More particularly, ANSI C63.19 specifies that the electric field and magnetic field generated by portable communication device RF transmissions be below certain thresholds proximate to the portable communication device's earpiece. While the electric field and magnetic field proximate to the portable communication device's earpiece can be reduced by an overall reduction in the RF transmission electric and magnetic fields, maintaining such reduced electric and magnetic fields significantly impacts the transmission and reception efficiency of the portable communication device.
Thus, there is an opportunity to develop an RF antenna system for a portable communication device that produces a limited electric field and magnetic field behavior near an earpiece thereof without significantly impacting the transmission and reception efficiency of the portable communication device. Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background of the disclosure.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
Before describing in detail embodiments that are in accordance with the present invention, it should be observed that the embodiments reside primarily in combinations of apparatus components related to antenna systems. Accordingly, the apparatus components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.